Link track refacing apparatus



Jan. 30, 1962 T. G. BRASHEAR, JR., ETAL 3,019,328

LINK TRACK REFACING APPARATUS Filed April 14, 1958 5 Sheets-Sheet 1 INVENTORS run/van a. ems/1545.12 0/9557 LEADER THE IR ATTORNEYS Jan. 30, 1962 T. s. BRASHEAR, JR., ETAL 3,019,328

LINK TRACK REFACING APPARATUS Filed April 14, 1958 5 Sheets-Sheet 2 INVENTORS go/wssr LEADER W P THE/l? ATTORNEYS.

TURNER a. BRASHEAR, JR.

Jan. 30, 1962 T. G. BRASHEAR, JR, ETAL 3,

LINK TRACK REFACING APPARATUS R J 3 R; m A E mE w m WW5 m w mum n m A h 6 m R H m m MM r 0 wrw M. Z. Em 5.25m ina? I N N w {KI mm II iIFH 1w; i

a1 a j Jan. 30, 1962 11s. BRASHEAR, JR., ETAL 3,019,328

LINK TRACK REFACING APPARATUS Filed April 14, 1958 5 Sheets-Sheet 4 VI: II" v I A Q 1\\! t g 6 f Z9 E 73 I u $0 k mm INVENTORS 65' T UR/VEI? G. BRASHEAIEJR IQORES T LEADER W 49% Tag/R ATTORNEYS '1". cs. BRASHEAR, JR., ETAL 3,019,328

5 Sheets-Sheet 5 Filed April 14, 1958 WELDING cmcuns M V 9? INVENTORS' i TURNER 6'. BRASHEARMR.

g g/PEST LEADER MFKM THE/I? ATTORNEYS 3,019,328 LINK TRACK REFACING APPARATUS Turner G. Brashear, In, El Cerrito, and Forest Leader,

(Bakland, Calif assignors to L & B Welding Equipment, Inc, Berkeley, (Ialifi, a corporation of California Filed Apr. 14, 1958, Ser. No. 728,235 12 Claims. 7 (Cl. 219-125) Our invention relates to the refacing of metal parts and more particularly to the refacing of the worn links of the link tracks of a tractor or like machine.

Tractors or like machines normally operate under conditions and environments which exposes the link tracks to severe wear. The cost of replacing worn tracks is high, and if the worn tracks can be restored to their original dimensions economically, this manner of solving the problem is to be preferred.

Among the objects of our invention are:

(1) To provide a novel and improved apparatus for refacing of worn metal parts;

(2) To provide a novel and improved apparatus for refacing of worn link tracks;

(3) To provide a novel and improved apparatus for refacing of worn link tracks quickly and in an effective and economical manner.

Additional objects of our invention will be brought out in the following description of a preferred embodiment of the same, taken in conjunction with the accompanying drawings, wherein;

FIG. 1 is a front view in elevation of the apparatus of partying drawings, wherein:

FIG. 2 is an end view in elevation of the apparatus of FIG. 1; 1

FIG. 3 is a plan view of the work supporting bed of the apparatus of FIG. 1 and associated work aligning mechanism; 7

FIG. 4 is an enlarged view depicting in detail the construction of the work aligning mechanism of FIGS; FIG. 5 is a view in section taken in the plane 55 of FIG. 2; I g p 1 FIG. 6 is a view in section taken in the plane 6--6 of FIG. 1;

FIG. 7 is a view inelevation of a Welding head assembly of the apparatus of FIG. 1 shown in relationship to I the work;

FIG. 8 is a view of the Welding head assembly of FIG. 7 in a plane at right angle to the view of FIG. 7;

FIG. 9 is an enlarged view depicting in detail, overhead drive mechanism for the welding assembly of the apparatus of FIG. 1;

FIG. 10 is an enlarged view depicting in detail, stabilizing means associated with the welding assembly of FIG. 1; I f

FIG. 11 is a control circuit employed in the ing of the apparatus of FIG. 1;

PEG. 12 is a three dimensional view 'of an assembly functionfor use in laying out a pattern strip employed in the apparatus of FIG. 1 for controlling a welding schedule on work involved.

Referring to the drawings for details of our invention in its preferred form, the apparatus illustrated therein has been developed specifically for refacing link tracks 1 of the type involving a plurality of hingedly connected links 3, each of which comprises a ground engaging pad 5 affixed to a pair of spaced apart track components 7. These track components, at their ends, overlap adjacent aligned components of the track and ride the supporting rollers of a tractor (not illustrated), the overlapping characteristics of the track components serving to pro= vide for a smooth transfer of load from one link'to another of. the track.

' the refacing or a link track.

. facing frontwardly.

v3,019,328 Patented Jan.v 30,. 1962 Following the placement of a link track 1 to be refaced, on the bed plate 13, it is essential in the opera tion of the apparatus of the present invention, that the link track lie straight and parallel to the front beam 17 and with link components in substantially perfect alignment.

To accomplish this following the placingof the link track on the bed, we provide a pusher beam 23 on the bed plate in substantial parallelism with the front and rear beams, and connect the same to the rear beam with a plurality of double toggles 25 having an adjusting screw 27 common to the same, such adjusting screw being in drive connection to a motor 29 mounted on the frame, preferably below the adjusting screw 27 and in drive connection thereto, utilizing for this purpose, a. sprocket 33 on the screw and a drive chain 33 from the motor to the sprocket.

Above the bed and running substantially the full length thereof is an overhead track assembly 35 including a plurality of brackets 37 aflixed along the rear edge of the bed frame 15 and terminating above the bed plate 13, and an l beam monorail track 39 supported by said brackets 37.

Suspended from the overhead track is a welding assembly 41 adapted to move along the track for the entire length of the bed. This welding assembly includes a carriage comprising a truck 45 having suspension wheels 47 riding on the lower flanges of the track 39 and an inverted L bracket 49 suspended from the truck 45 with its horizontal arm 51 extending transversely of the link track bed plate 13, this bracket serving as the mounting for all of the essential welding equipment involved in Such welding equipment involves a pairof welding head assemblies 55. These welding head assemblies are supported for simultaneous vertical adjustment, from the horizontal arm 51 of the inverted L bracket, by providing such arm at each end with a depending guide sleeve 65, while extending downwardly into each of these guide sleeves, .is a vertical adjusting screw 66 having a drive sprocket 67 at its upper end, connected with the other by a drive chain 69. A motor 70, gear connected to one screw, thus drives both, Each of said vertical adjusting screws threadedly engages a telescoping sleeve 71 in each of the guide sleeves, while each of these telescoping sleeves, in turn, carries a block 73, which together with the other corresponding block, constitutes a supportfor a pair of rods 75 to provide for the slidable mounting of the Welding head assemblies.

- For this'purpose each welding head assembly includes a split mounting bracket 7 9 enabling the mounting bracket to be bolted to the rods for slidable movement thereon. Adjustment of each welding head assembly on these rods to the exclusion of the other weldinghead assembly is made possible by a screw 30 journalled in the blocks 73 and passing through one mounting bracket and threadedly engaging the mounting bracket of the welding head assembly which it is to control. Each of the screws carries a handle 81 at one end to permit individual manual adjustment of the welding head assemblies along the horizontal mounting bars. I

Provision is made also for effecting a conversion from such individual adjustment of the welding head assemblies to simultaneous adjustment of both welding head assemblies along the horizontal mounting rods, and this is accomplished by fixing a gear 33 on one of the adjusting screws adjacent the control handle thereon, while on the other adjusting screw, slidably keying a similar gear 85 which is adapted to be manually shifted into and out of mesh with the first gear, whereby, when shifted into mesh with the first gear, the rotation of one handle will control operation of both adjusting screws.

For the purpose of the present invention, the thread of one of these adjusting screws 34 is preferably a left hand thread, while that of the other is a right hand thread. When so provided, simultaneous adjustment of the welding head assemblies along the horizontal mounting rods 75 will cause the welding head assemblies to either approach or move away from each other, depending on the direction of rotation of such handle.

Each welding head assembly, besides the mounting bracket 75 involves a welding head 86 carried by the bracket.

Toward further accomplishing the objects of the present invention, it is quite desirable that the individual heads 36 be adjustable to the exclusion of each other, in both a forward and vertical direction. The individual horizontal adjustment is accomplished by dovetailing an upper section 89 of the horizontal portion of the mounting bracket 79 of the welding head assembly and controlling slidable adjustment thereof by a manually rotatable adjusting screw 91, the welding head being supported from the upper dove-tailed portion'of the bracket.

The individual vertical adjustment of each welding head is accomplished in a somewhat similar manner by dovetailing a portion 93 of the frontal section of the mounting bracket 79 and controlling it for vertical movement by a manually operated adjusting screw 95.

This vertically adjustable front portion of the welding head mounting bracket terminates at its lower end in a collar 97 in which is rotatably mounted the welding head 86 which includes a Wire feed drive motor 99 driving wire feed rollers 1191 through a gear train enclosed within a gear train housing 103.

Above and below the wire feed rollers are wire guides 105, 107 for controlling the path of movement of the wire to the work, from a storage reel 15% mounted above, on the horizontal arm 51 of the inverted L bracket 49. The collar mounting of the welding head permits of angular adjustment of the welding head, to permit feeding of the wire to the work at an angle, as when the surface to be worked on may not lie in a horizontal plane. To effect such angular adjustment, a manually rotatable worm 111 is mounted in each collar in threaded engagement with an arcuate rack 113 aflixed to the motor casing.

Supported at the front of each welding head is a flux hopper 115 provided with a valve controlled discharge hose 117 directed toward the work, in the neighborhood of the lower wire guide.

Movement of the welding assembly 41 along the overhead track 39 is accomplished by drive motor 121 operating a pinion 123 which is in mesh with a rack 125 mount ed against the underside of the track.

This motor is mounted on a platform 127 pivotallysecured at an intermediate point thereof to the truck 45, with the greater portion of the motor weight disposed behind the pivot axis so as to normally tilt the drive end upward and urge the pinion 123 into drive engagement with the rack 125.

The motor platform is provided with a depending tail flange 131. This is adapted to be engaged by a lift cam 133 carried on one end of a shaft 135 journalled in a pair of cars 1141 on the horizontal arm 51 of the inverted L bracket. The cam is under control of a handle 143 on the other end of the shaft 135, whereby upon rotating the cam through an angle, the motor platform may be reversely tilted to disengage the pinion 123 from the rack 125 and thus halt travel of the Welding assembly.

To stabilize the welding assembly against swaying during its travels over the link track supporting bed, the overhead track 319 is disposed to one side of the center of gravity of the welding assembly, thereby imparting to the assembly, the tendency to swing from its desired operating position. The assembly is supported in its operating position, by abutting it against a longitudinally disposed rail 147 carried by brackets 149 mounted on the track brackets 37. This rail will lie adjacent the path of travel of the vertical arm of the inverted L bracket andaccordingly abutment takes place at this point, where the bracket arm will be provided with an adjustable roller or rollers 151 to assure a minimum of friction against the rail 147 during travel of the welding assembly.

With respect to the track 1 to be refaced, each of the welding heads may be individually adjusted to bring it in line with a suitable starting point on the track, each welding head being assigned to one side of the link track. Preferably the individual adjustment is such that the Welding heads are lined up with the outer edges of the link components, and then by coupling the gears 83 and for simultaneous horizontal adjustment of the welding heads, they may be adjusted toward each other for successive traversals of the welding assembly along the track until the entire surface of the track link is covered.

In preparing the link track for the deposition of metal along the exposed surfaces of the link components as the welding assembly moves along the link track, this track is buried in flux up to the upper exposed surfaces of the link components, which surfaces are subsequently covered with flux from the hoppers as the assembly moves along the track to be serviced. This welding procedure is known as submerged arc welding.

During such procedure, it is of course quite important that the aligned link components not be bridged by metal deposited from the welding wire and thereby welded together, as this would nullify the hinge connection between links and rigidify the track and render it useless.

As a safeguard against this, and this constitutes an important feature of the present invention, we provide along the front edge of the bed frame, a control pattern preferably in the form of a strip 152 of transparent sheet material such as plastic, and apply thereto, an opaque pattern 153 of the spacing between aligned link components, this pattern being repeated in accordance with the distance between such spacings on the link track.

Carried by the welding assembly is a bracket 154 which terminates alongside the edge of the plastic strip in a depending bar 155 on which may be slidably mounted, a light source 156 and a light responsive element 157 with the plastic strip disposed between the two. The slidable mounting of the light source 156 and light responsive element 157 permits of vertical adjustment of each of these two devices to properly locate the same in alignment vertically with respect to the intermediate patternstrip. Longitudinal and transverse adjustment of the two elements as a unit with respect to the patterns on the pattern strip, is made possible by the makeup of the supporting bracket 154, such bracket comprising a flange 158 depending from one of the welding heads and terminating in a horizontal rectangular sleeve 159 in which is slidably positioned a horizontal bracket arm 160 having on its underside, a rack 161 for engagement with a pinion mounted within the sleeve and controlled by a handle 162 externally thereof.

The horizontal bracket arm 160 carries at its free end a similar sleeve 163 disposed longitudinal of the bed frame and slidably receiving an arm 164 to one surface of which is affixed a rack 165 for engagement with a pinion supported within the sleeve and controlled externally thereof by a control knob 166. At the exposed end of thisarm is the depending rod 155 which carries the light source 156 and light responsive element 157.. By means I circuits normally involved in a welding assembly, the feeding of the welding wire and establishing of the arc may be controlled in accordance with the spacing between aligned link components, so as to deposit metal only during travel of the welding heads over the exposed surfaces of the link components and not during those briefintervals of time when the welding heads are moving from one link component to another.

, while the other end is connected to the anode 168 by outlined area to complete the stencil.

. energizes the welding heads while opening of the switch will de-energize them.

In refacing or building up the surfaces of the link components one or two passes will be made along the outer edges of the linkcomponents as these edges will probably be worn to a greater degree than the rest of the surfaces to be built up. Following this, the welding heads will be shifted toward each other sufficient to deposit metal adjacent the metal previously deposited dur ing the preceding pass, and in this manner cover the entire surface to be refaced.

in preparing the pattern strip, a stencil'184 of the spacing between aligned link components of the track is first prepared. This may be done by outlining a pattern of such spacing on a section of stencil material preferably aterial of a transparent character, and then cutting the This is not a critical operation, and one stencil as thus prepared, may be deemed representative of the space areas throughout the extent of the track.

This stencil is then installed in a guide assembly for I determining the successive locations of the space areas way of the light responsive element 157 and a master cuit is similarly obtained from the, same voltage source which is connected across this condenser through a reversely connected rectifier 131, also preferably of the selenium type. b

If the alternating current supply source referred to has a value of 115 volts, each of the condensers will register peak voltages which will be of the order of 150 volts. In the circuits as thus described, the two condensers will be effectively connected in series across the light responsive element 157 and the potentiometer 1712 thereby placing a total voltage of the order of 300 volts across these two components in series. The portion of this voltage employed for grid excitation, can therefore be adjusted between very Wide limits and may he so selected that.

with the light responsive element dark, and evidencing a high value of resistance, the master relay will be unenergized. Then when the light responsive element is eX- posed to a light source and its resistance. accordingly decreased to a relatively low value, the master relay may become energized and trigger oil" its associated circuits in the welding assembly.

lnasrnuch'as the welding circuits are conventional and depend upon the type of welding employed, we have designated them generally, and show them as controlled by the master relay winding 174. The triggering circuit and welding circuits'rnay be confined in a housing 182 mounted beneath the horizontal arm Slot the inverted L shaped bracket 4%.

,With the light source and light responsive element properly positioned with respect to the patterns on the plastic strip, it will be apparent that the welding assembly may be driven the whole length of the link track, during the course of which, the welding heads will be operative during travel over the surfaces of the link components, but during passage of the welding assembly across the gaps separating the aligned link components, the Wire feed motor will be stopped and the arc extinguished, so that deposition of metal can not occur during these brief intervals.

To energize the welding heads intermittently as desired,

a switch 183 may be introduced in the charging circuit of the plate voltage condenser 175. Closing of this switch on the pattern strip in relationship to a track disposed on the bed for servicing and from which the stencil was prepared. The reproduction of the space areas on the pattern strip may be accomplished by spraying an opaque liquid over the cut out portion of the stencil, or by any other convenient means.

Theguide assembly referred to involves a rod 185, at an intermediate point of which is slidably mounted a control stylus 137 and at one end a slidably mounted crossarm'l91. In each end of this cross arm is adjustably mounted a vertical rod 195 carrying at its lower end, a suction cup 197. These suction cups constitute means for holding a stencil. i

At the opposite end of the rod 135, the rod carries I a yoke 19! adapted to embrace the rail 147 and support rail.

up for operation. I

a pair of spaced rollers 199 in sliding contact with such This yoke with its spaced rollers in contact with the rail, serves to support the rod 185 transversely of the track supporting bed.

With the control stylus 187 adjusted with its point over one of the rows of aligned link components, and with the cross arm 191 adjusted on the rod 185 to bring the pattern stencil in contact with the upper surface of the pattern strip, the space area patterns may be applied to the pattern strip in accordance with their locations along the rows of aligned link components.

Once the pattern strip has been prepared for the par- 'ticular track to be serviced, it is then only necessary to correlate the positions of the welding heads and the light source, for any point on the track, to set the machine From the foregoing description of our invention in its preferred form, it will be apparent that the same fulfills an the objects attributed thereto, and while we have disclosed but one embodiment of the invention, it will be each comprising a. ground engaging pad affixed to a pair of spaced apart track components, which. overlap adjacent aligned components of thetrack and ride the supporting rollers of a tractor, said apparatus comprising a link track supporting bed for laying out such track with the spaced apart track components facing upwardly, said track supporting bed including a bed plate, a frame supporting said bed plate, an overhead track assembly running substantially the length of said bed, said over- 7 head track assembly including a plurality of brackets afiixed to said bed frame and terminating above said bed plate, and a track supported by said brackets, a welding assembly suspended from said track, said welding assembly including a pair of welding heads, means for simultaneously adjusting said welding heads, means for individually adjusting each of said welding heads to the exclusion of the other, a flux hopper mounted on each of said welding heads and having means for controlling discharge of flux therefrom, a pair of welding wire storage reels, means for driving said welding assembly along said overhead track, means stabilizing said welding assembly against sway during movement along said overhead track; and means for controlling non-operating periods of said welding heads as said welding assembly is driven along its supporting track over such link track, said means comprising a light transmitting pattern strip, means supporting said pattern strip parallel to a link track disposed on said bed plate, said pattern strip having a succession of opaque patterns corresponding in shape to the spacing between adjacent aligned link components and spaced apart in accordance with the distance between such spacings, a bracket supported from said welding assembly and carrying a light source disposed to one side of said pattern strip and an aligned light responsive device to the other side of said pattern strip, and means responsive to changes in said light responsive device as said light source and light responsive device move along said pattern strip, for halting feed of wire during traversal of said patterns.

2. Welding apparatus for performing work on a row of aligned surfaces spaced from one another, comprising a welding head, overhead track means substantially paralleling such row of aligned surfaces and supporting said welding head for movement over such surfaces, means for aligning said welding head with a path to be traveled over such row, means for energizing said welding head to feed welding wire to work and establish and maintain an arc during travel of said welding head over such surfaces, and de-energizing the same during travel of said welding head over areas representing the spaces between successive aligned Work surfaces, said means including a pattern strip having patterns thereon representative of such surfaces and space areas therebetween, means supporting said pattern strip in parallel relationship to such row of aligned work surfaces, means movable along said pattern strip with travel of said welding head along its associated row of aligned work surfaces and responsive to changes in pattern strip characteristics for controlling the on and 01f periods of said welding head, said last means including carrier means mounted for movement with said welding head and along said pattern strip, a light source on said carrier means to one side of said pattern strip and a light responsive device on said carrier means to the other side of said pattern strip, and a triggering circuit for said welding head, said triggering circuit including said light responsive device.

3. Welding apparatus for performing work on a row of aligned surfaces spaced from one another, comprising a welding head, overhead track means substantially paralleling such row of aligned surfaces and supporting said welding head for movement 'over such surfaces, means for aligning said welding head with a path to he traveled over such row, means for energizing said welding head to feed welding wire to work and establish and maintain an arc during travel of said welding head over such surfaces, and de-energizing the same during travel of said welding head over areas representing the spaces between successive aligned work surfaces, said means including a pattern strip having a succession of patterns thereon conforming to the general shape, size and distribution of the space areas along such row of aligned surfaces, said pattern strip having different physical characteristics than said patterns, means supporting said pattern strip in parallel relationship to such row of aligned work surfaces, means connected to one of said welding heads and movable along said pattern strip with travel of said welding head along its associated row of aligned work surfaces and responsive to changes in pattern strip characteristics, for controlling the on and oif periods of said welding head.

4. Welding apparatus for performing work on a pair of rows, each involving a plurality of aligned surfaces spaced from one another, comprising a pair of welding heads, overhead track means substantially paralleling such rows of aligned surfaces and supporting said pair of welding heads for movement over such surfaces, means for aligning one of said Welding heads with a path to be traveled over one of such rows, means for aligning the other of said welding heads with a path to be traveled over the other of such rows, means for energizing each of said welding heads to feed welding wire to work and establish and maintain an arc during travel of said Welding heads over such surfaces, and de-energizing the same during travel of said welding heads over areas representing the spaces between successive aligned work surfaces, said means including a pattern strip having a succession of patterns thereon conforming to the general shape, size and distribution of the space areas along either row of aligned surfaces, said pattern strip having different physical characteristics than said patterns, means supporting said pattern strip in parallel relationship to such rows of aligned Work surfaces, means connected to one of said welding heads and movable along said pattern strip with travel of said welding head along its associated ,row of aligned work surfaces and responsive to changes in pattern strip characteristics, for controlling the on and oif periods of both said welding heads.

5. Welding apparatus for performing work on a pair of rows, each involving a plurality of aligned surfaces spaced from one another, comprising a pair of welding heads, overhead track means substantially paralleling such rows of aligned surfaces and supporting said pair of Welding heads for movement over such surfaces, means for aligning one of said welding heads with a path to he traveled over one of such rows, means for aligning the other of said welding heads with a path to be traveled over the other of such rows, means for thereafter simultaneously adjusting both said welding heads to traverse an adjacent path of travel, each along its associated row, means for energizing each of said welding heads to feed welding wire to work and establishing and maintaining an arc during travel of said welding heads over such surfaces, and de-energizing the same during travel of said welding heads over areas representing the spaces between successive aligned work surfaces, said means including a pattern strip having a succession of patterns thereon conforming to the general shape, size and distribution of the space areas along either such row of aligned surfaces, said pattern strip having different light transmitting characteristics than said patterns, means supporting said pattern strip in parallel relationship to such rows of aligned work surfaces, means connected to one of said welding heads and movable along said pattern strip with travel of said welding head along its associated row of aligned work surfaces and responsive to changes in pattern strip characteristics, said means comprising a light source to one side of said pattern strip and a light sensitive device to the other side of said pattern strip and in alignment with said light source, and control means including said light sensitive device for determining the on and off periods of both welding heads.

6. Apparatus for refacing link tracks or the like of the type involving a plurality of hinged connected links, each comprising a ground engaging pad afiixed to a pair of spaced apart track components, which overlap adjacent aligned components of the track and ride the supporting rollers of a tractor, said apparatus comprising a link track supporting bed for laying out such track with the spaced apart track components facing upwardly, a track assembly I acrea e assembly including a pair of welding heads, each disposable above a row of aligned track components, a pair of welding wire storage reels, above said welding heads,

means for driving said welding assemblyalong said track,

and means responsive to movement of said welding assembly over such link track, determined in accordance with the lengths of surfaces and intervening spaces in the paths travelled by said welding heads along said track components from one end to the other of such track, for

controlling on and off periods of said welding heads in comprising a ground engaging pad afiixed to a pair of spaced apart track components, which overlap adjacent aligned components of the track and ride the supporting rollers of a tractor, said apparatus comprising a link track supporting bed for laying out such track with the spaced apart track components facing upwardly, an overhead track assembly running substantially the length of said bed, a. welding assembly suspended from said track assembly, said welding assembly including a pair of welding heads, means for adjusting one of said welding heads with respect to one set of aligned link track components to execute a path of travel thereover, means for adjusting the other of said welding heads with respect to the other set of aligned link track components to execute a path of travel thereover, and means for simultaneously shifting both said welding heads to a different path of travel of each over its associated link track components, a pair of welding wire storage reels above said welding heads, means for driving said welding assembly along said overhead track, and means for controlling on and off periods of said welding heads in accordance with such aligned link components and spaces therebetween as said welding assembly is driven along its supporting track over such link track, said means comprising a light transmitting pattern strip, means supporting said pattern strip parallel to a link track disposed on said bed plate, said pattern strip having a succession of opaque patterns corresponding in shape to the spacing between adjacent aligned link components and spaced apart in accordance with the distance between such spacings, a bracket supported from said welding assembly and carrying a light source disposed to one side of said pattern strip and an aligned light responsive device to the other side of said pattern strip, and means responsive to changes in said light responsive device as said light source and light responsive device move along said pattern strip, for determining ene'rgization and de-energiaation of said welding needs.

3. Welding apparatus for refacing tractor tracks or the like involving a pair of rows of track components to be refaced, means for supporting such track with such track components facing upwardly, a pair of welding heads, track means substantially paralleling such rows of aligned track components and supporting said welding heads for movement over such track components to be refaced, means for aligning one of said welding heads with a path to be traveled over one of said rows, means for aligning the other of said welding heads with a path to be traveled over the other of said rows, and means for thereafter simultaneously adjusting both said Welding heads to traverse an adjacent path of travel, each along its associated row. I l

9. Welding apparatus for refacing tractor tracks or the like involving a pair of rows of track components to be refaced, means for supporting such track with such track components facing upwardly, means for straightening such track to bring the track components of each row into sub stantially perfect alignment, said means including a pusher beam located alongside such track, a plurality of double v 10 a toggle means behind and connected to said pusher beam, means behind said toggle means and fixedly secured to said track supporting means for anchoring said toggle means, toggle adjusting screw means threadedly passing through aplurality of said toggles and a drive connection to said screw means, a pair of welding heads, overhead track means substantially paralleling such rows of aligned track components and supporting said welding heads for movement over such track components to be refaced, means for aligning one of said welding heads with a path to he traveled over one of such rows, means for aligning the other of said welding heads with a path to be traveled over theother of such rows, and means for thereafter simultaneously adjusting both said welding heads to traverse an adjacent path of travel, each along its associated row.,

10. Welding apparatus for performing work on a row of aligned work surfaces spaced from one another, comprising a welding head, track means substantially paralleling such row of aligned work surfaces and guiding said welding head along 'a path of movement over such aligned work surfaces, means for aligning said welding head with a pathto be traveled over such row of aligned work surfaces, and means determined by the lengths of surfaces and intervening spaces to be traversed by said welding head during movement of said welding head along said track means for energizing said welding head to establish and maintain an arc during travel over such aligned surfaces and de-energizing such welding head to extinguish such arc during travel across the spaces between such aligned surfaces, said last means including a plurality of successively arranged spaced patterns indicative of the length and spacingof said aligned work surfaces, at light source, a light responsive device, carrier means supporting said light source and said light responsive device in alignment with said light source to one side of said successively prising a welding head, track means substantially parallelmg such row of aligned work surfaces, means for aligning said welding head with a path to he traveled over such row of aligned work surfaces, means for energizing said welding head during travel of said welding head over such aligned work surfaces and tie-energizing the same during travel of said welding head over areas representing the spaces between successive aligned work surfaces, said means including a succession of patterns supported in a row in parallel relationship to such row of aligned work surfaces, said patterns being spaced from each other in accordance with the areas representing the spaces between such aiigned work surfaces, means movable along said row of patterns with travel of said welding head along its associated row of aligned work surfaces and responsive to said patterns as they are thus traversed, for controlling the on and off periods of said welding head, said last means including a light source, a light responsive device, carrier means supporting said light source and said light responsive device in alignment with said light source to one side of said row of patterns and said light responsive device to the other side of said row of patterns, and means for moving said carrier means relative to said row of patterns in accordance with movement of said welding head along said row of aligned work surfaces.

12. Welding apparatusfor performing work on parallel similar rows of aligned work surfaces spaced from one another with the work surfaces of one row mechanically coupled to opposite work surfaces of the other row, comprising a welding head for each row, track means substantially paralleling such rows of aligned work surfaces and 11 guiding such Welding heads'along a path of movement over such surfaces in its associated row, means for aligning said Welding heads, each with a path to he traveled over its associated row of aligned work surfaces, and

12 any linear distance between successive aligned work surfaces and cooperating with said triggering circuit component during passage of said component across each pattern to de-energize said welding head from an enermeans for energizing said welding heads to establish and 5 gized condition during each such pattern passage.

maintain an are at each during travel over such aligned surfaces and de-energizing said welding heads during travel across spaces between such aligned surfaces, said 7 last means comprising a triggering circuit for said welding heads, said triggering circuit including a component movable with said welding heads and a single plurality of patterns disposed in a row paralleling the paths of movement of said welding heads, and spaced from each other in accordance with the areas representing the spaces between successive aligned Work surfaces, said patterns, each having a linear dimension in the direction of travel of said triggering circuit component, substantially equal to References Cit-ed in the file of this patent UNITED STATES PATENTS 1,838,899 Arnold Dec. 29, 1931 2,185,381 Munch et a1. Jan. 2, 1940 2,269,754 Bernhardt et a1 Jan. 13, 1942 2,277,489 Harrison Mar. 24, 1942 2,401,722 Clapp June 11, 1946 2,466,497 Smith Apr. 5, 1949 2,501,893 Dudley Mar. 28, 1950 2,683,432 Schanz July 13, 1954 

